<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
  <style>
    #bx{color: red}
    .c1{color: blue}
    h3,#bx,.c1{background-color: aqua}
    input[type="text"]{color: red}
    /*属性选择器*/
    input[type="password"]{color: blue}
    *{border: 1px solid red}
  </style>
</head>
<body>
<input type="text" placeholder="用户名">
<input type="password" placeholder="密码">
<h3>这是h3</h3>
<p>电视机</p>
<p class="c1">洗衣机</p>
<p id="bx">冰箱</p>
<div class="c1">香蕉</div>
<div>苹果</div>

</body>
</html>